Generic differential pressure measuring pickups are described, for example, in the patents U.S. Pat. No. 5,955,675, U.S. Pat. No. 5,922,965, U.S. Pat. No. 6,055,863, and U.S. Pat. No. 7,080,558.
In the differential pressure measuring pickups according to the patents mentioned, the seals used are, in particular, metallic sealing rings, which, like the pressure input openings and the separating diaphragms, are arranged in recesses in the process interfacing surface, wherein the depth of the recesses determines the compression of the sealing rings, if it is assumed that the process interfacing surface of the differential pressure measuring pickup is tensioned during operation against a complementary mating surface of a flange.
In this way, the surface pressure of the sealing rings, which, on the one hand, must be high enough that the seal can withstand a media pressure and, on the other hand, must be as low as possible, so that the measurement characteristics of the differential pressure measuring pickup are not impaired, is essentially defined by the depth of the recesses in the process interfacing surface.